E. Proposed theoretical explanation. There is no standard explanation that we
know of, for all these observations in the three investigated glass types. Clustering
of Fe-ions is not an explanation, for \(n\) (Fe) as determined from the naive LL-fitting
of SQUID-data is always greater than that determined by the MS. Kramers
doubling of the \(J\) =5/2 Fe\(^{3+}\) -spin spectrum would not help, for it would
result in a linear dependence of the energy levels and splittings on \(H\) . Quenching
of the orbital moments for Fe-ions by the local-“crystal” field is believed to be
complete in the multi-silicates anyway [1]}, a reason why \(g\) =2 is
expected to be correct here, for both Fe\(^{2+}\)  and for Fe\(^{3+}\)  [2]}.
